As a wind turbine used for a wind generator, there are known a wind turbine in which a pitch angle of a wind turbine rotor blade is fixed and a wind turbine in which the pitch angle is variable.
As a mechanism which changes the pitch angle of the wind turbine rotor blade, there is known a mechanism which converts linear motion of a rod in a hydraulic cylinder into rotation around an axis of the wind turbine rotor blade as described in Patent Citation 1.
As shown in Patent Citation 2 or the like, there is proposed a mechanism in which a gear is provided around a blade rotating wheel, a pinion gear meshing with this gear is rotated by an electric motor, the blade rotating wheel is rotated and this rotation is converted into rotation around an axis of a wind turbine rotor blade.
In this case, it is also proposed to use a belt instead of the gear.    Patent Citation 1: Japanese Unexamined Patent Application, Publication. No. 2003-148321    Patent Citation 2: Japanese Unexamined Patent Application, Publication No. 2003-56448